Hydrophobically modified chitosan microparticles were produced by various syntheses carried out as heterogeneous phase reactions. Perfluorinated carbonyl components such as carbonic acids and acid chlorides were used as hydrophobization agents. To enhance the layer stability preceding cross-linkages between the chitosan macromolecules were introduced. These cross-linkages involve some of the chitosan amino groups. The use of a highly reactive alkylene-maleic anhydride copolymer produces cross-linkages and hydrophobizes the chitosan layer simultaneously in a one-step reaction. The heterogeneous reactions serve as model reactions for the hydrophobization of chitosan films deposited on supports.